Retortable plastic container

ABSTRACT

A retortable plastic container includes a finish portion and a main body portion that is unitary with the finish portion and that includes a sidewall having an inner surface that defines an interior space and an outer surface. The sidewall is preferably fabricated from a material comprising a plastic and is shaped so as to have at least one radially inwardly extending annular projection defined therein that provides reinforcement against radial expansion of the main body portion during the retort process. In addition, a transition portion between a main body of the container and the bottom of the container preferably includes at least one annular step that increases the rigidity of the bottom portion of the container.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to the field of packaging technology, and more specifically to retortable plastic containers, which are used for packaging a number of different products, such as baby foods.

[0003] 2. Description of the Related Technology

[0004] Retortable containers, which may be defined as containers that are designed to withstand high temperatures, are used in the packaging of products such as baby foods. The retort process is used to sterilize and/or cook the material within the container. Historically, glass containers were used for this purpose. More recently, however, plastic retortable containers have gained widespread acceptance in the industry. One problem with the use of plastic containers is that the shape of the container will tend to distort at high temperatures, particularly when the high temperature causes high pressures to be developed within the container. This distortion can cause failure of the container or the seal between the container and its closure and, in severe cases, the container never returns to its original shape.

[0005] A certain amount of resistance to temperature and pressure induced deformation can be imparted to the container by increasing the sidewall thickness of the container, however doing so substantial increases the cost of the container. An alternative solution that has been proposed involves designing one portion of the container to be flexible so as to accommodate the need for expansion when pressure within the container increases during the retort process. In U.S. Pat. No. 5,217,737, for example, the bottom portion of the container is designed to be flexible so as to accommodate the need for expansion.

[0006] A need exists for a retortable plastic container that exhibits an increased resistance to deformation during the retort process.

SUMMARY OF THE INVENTION

[0007] Accordingly, it is an object of the invention to provide a retortable plastic container that exhibits an increased resistance to deformation during the retort process.

[0008] In order to achieve the above and other objects of the invention, a retortable plastic container that is constructed according to a first aspect of the invention includes a finish portion; and a main body portion that is integral with the finish portion, the main body portion comprising a sidewall having an inner surface that defines an interior space and an outer surface, the sidewall being fabricated from a material comprising a plastic material, and wherein the sidewall is shaped so as to have at least one radially inwardly extending annular projection defined therein, the annular projection providing reinforcement against radial expansion of the main body portion during the retort process.

[0009] A retortable plastic container that is constructed according to a second aspect of the invention includes a finish portion; a main body portion that is integral with the finish portion, the main body portion comprising a sidewall having an inner surface that defines an interior space and an outer surface, the sidewall being fabricated from a material comprising a plastic material; a bottom portion; and a bottom transition portion connecting the bottom portion to the main body portion, the bottom transition portion having at least one inwardly radiused annular step defined therein.

[0010] These and various other advantages and features of novelty that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a side elevational view of a retortable plastic container that is constructed according to a preferred embodiment of the invention;

[0012]FIG. 2 is a magnified view of area 2-2 in FIG. 1;

[0013]FIG. 3 is a magnified view of area 3-3 in FIG. 1;

[0014]FIG. 4 is a cross-sectional view taken along lines 4-4 in FIG. 1; and

[0015]FIG. 5 is a cross-sectional view taken along lines 5-5 in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0016] Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to FIG. 1, a retortable plastic container 10 that is constructed according to a preferred embodiment of the invention includes a finish portion 12 and a main body portion 14 that is unitary with the finish portion 12. Container 10 further includes a bottom portion 16 and a bottom transition portion 18 that is unitary with the bottom portion 16 and the main body portion 14. The entire container 10 is preferably fabricated from a multilayer plastic material having a first, inner layer of polypropylene, a second, adhesive layer, a third, barrier layer fabricated from a material such as EVOH, a fourth adhesive layer, a fifth layer of reground polypropylene and a sixth, outer layer of polypropylene. It should be understood that this material is provided as a preferred example only, and that the invention as described and claimed herein is equally applicable to a retortable plastic container that is fabricated from any one of a virtually infinite possible selection of plastic materials and laminates.

[0017] Referring now to FIG. 2, which is a magnified view of area 2-2 in FIG. 1, it will be seen that the sidewall 22 of container 10 preferably has an outer surface 24 and an inner surface 26. According to one particularly advantageous aspect of the invention, sidewall 22 is shaped so as to define at least one radially inwardly extending annular projection 20, the purpose of which is to provide reinforcement against radial expansion of the main body portion 14 of the container 10 during the retort process. Preferably, the inwardly extending annular projection 20, a cross-section of which is depicted in FIG. 4, is shaped so as to have an inwardly extending corner 28 that is shaped so as to have a radius of curvature that is no more than 0.015 inches. Preferably, annular projection 20 also has a depth D_(R) that is preferably within a range of about 2.0 to about 7.0 percent of a maximum matter radius R_(MAX) of the container 10, and is most preferably about 4.0 percent. Inwardly extending corner 28 preferably is shaped so as to have an angle α that is between 80 degrees and 100 degrees, and that is more preferably approximately 90 degrees.

[0018] Referring now to FIG. 5, it will be seen that according to another advantageous aspect of the invention bottom transition portion 18 has at least one inwardly radiused annular step, which provides increased rigidity against expansion to the lower portion of the container 10. In the preferred embodiment, a first inward step 30 is defined by a first concave radius R₁ that is defined on the inner surface 26 of the sidewall 22 and a second concave radius R₂ that is defined on the outer surface 24. A second inward step 30 is defined by a third concave radius R₃ on the inner surface 26 and a fourth concave radius R₄ on the outer surface 24. A fifth radius R₁ on the inner surface 26 completes the transition to the bottom portion 16 of the container 10.

[0019] Preferably, the radii that define the first and second steps 30, 32 have a radius of curvature that is no more than {fraction (3/8)}inch, and that is more preferably within a range of between about {fraction (1/32)} of an inch and ⅛ in an inch.

[0020] It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

What is claimed is:
 1. A retortable plastic container, comprising: a finish portion; and a main body portion that is integral with said finish portion, said main body portion comprising a sidewall having an inner surface that defines an interior space and an outer surface, said sidewall being fabricated from a material comprising a plastic material, and wherein said sidewall is shaped so as to have at least one radially inwardly extending annular projection defined therein, said annular projection providing reinforcement against radial expansion of said main body portion during the retort process.
 2. A retortable plastic container according to claim 1, wherein said annular projection is shaped so as to have an inwardly extending corner that is shaped so as to have a radius of curvature that is no more than 0.015 inch.
 3. A retortable plastic container according to claim 1, wherein said annular projection has a depth that is at least 2% of a maximum outer radius of the container.
 4. A retortable plastic container according to claim 1, wherein said annular projection is positioned proximate to said finish portion.
 5. A retortable plastic container according to claim 1, wherein said annular projection is shaped as to have an inwardly extending corner, and wherein said corner is angled at an angle that is between 80 degrees and 100 degrees.
 6. A retortable plastic container according to claim 5, wherein said angle is between 85 degrees and 95 degrees.
 7. A retortable plastic container according to claim 6, wherein said angle is approximately 90 degrees.
 8. A retortable plastic container according to claim 1, further comprising a bottom portion and a bottom transition portion connecting said bottom portion to said main body portion, said bottom transition portion having at least one inwardly radiused annular step defined therein.
 9. A retortable plastic container according to claim 8, wherein said inwardly radiused annular step has a radius that is no more than ⅜ of an inch.
 10. A retortable plastic container according to claim 9, wherein said radius is within a range of between about {fraction (1/32)} of an inch and ⅛ of an inch.
 11. A retortable plastic container according to claim 8, wherein said bottom transition portion as a plurality of inwardly radiused annular steps defined therein.
 12. A retortable plastic container, comprising: a finish portion; a main body portion that is integral with said finish portion, said main body portion comprising a sidewall having an inner surface that defines an interior space and an outer surface, said sidewall being fabricated from a material comprising a plastic material; a bottom portion; and a bottom transition portion connecting said bottom portion to said main body portion, said bottom transition portion having at least one inwardly radiused annular step defined therein.
 13. A retortable plastic container according to claim 12, wherein said inwardly radiused annular step has a radius that is no more than ⅜ of an inch.
 14. A retortable plastic container according to claim 13, wherein said radius is within a range of between about {fraction (1/32)} of an inch and ⅛ of an inch. 